1. Field of the Invention
The present invention relates to a tough panel integrated flat display device which can improve reliability.
2. Description of the Related Art
Touch panels are input devices replacing keyboards or mousse used in the industrial fields of computer-aided design (CAD), production systems, game consoles, kiosks, point-of-sale (POS), or medical services. The touch panel is installed on a display surface that is an output device so that a user can manipulate various input operations, for example, directly pressing the display surface at a particular position while viewing an output display surface.
The touch panel is classified into an electrostatic capacity type and a resistant film type according to its operational principle. In the electrostatic capacity type touch panel, while charge/discharge states of an electrostatic capacity are repeated in a single transparent conductive film or a transparent conductive glass, a small amount of charges are accumulated according to a combined capacity of a stylus that is a pen type input device and the transparent conductive film at a contact point of the touch panel pressed by a user. Then, the amount of the charge is read from four input points and calculated into a coordinate value. Thus, electric power must be supplied to the stylus in the electrostatic type touch panel.
In the resistant film type touch panel, while a voltage is applied to two transparent conductive films (resistant films) facing each other, a user presses the touch panel, thus forming a contact point where the two conductive films contact each other. Then, a change in voltage or current at the contact point is read and calculated into X and Y coordinate values. A bus bar (electrode) is needed to read the voltage or current change at the contact point.
The resistant film type touch panel includes a pad connected to an external drive unit to apply a voltage to the resistant film. The pad of the touch panel contacts a flexible circuit board pad located at an end of a flexible circuit board connected to the external drive unit. The pad of the flexible circuit board and the pad of the touch panel are electrically connected to each other by thermally pressing an anisotropic conductive film using a bonding machine. The anisotropic conductive film is an adhesive film including conductive particles.
The touch panel of a general display device has the following disadvantages in the bonding process of the flexible circuit board.
As described above, the anisotropic conductive film is melt at high temperature and then pressed in the bonding process of the flexible circuit board. Since the anisotropic conductive film is not sufficiently filled up between the pad of the touch panel and the pad of the flexible circuit board, contact therebetween may be defective.
That is, in a general touch panel integrated display device, since the pad of the touch panel and the pad of the flexible circuit board are formed to each other, during the bonding process, pressure is locally generated only in an area where the pad of the touch panel and the pad of the flexible circuit board are located so that the anisotropic conductive film is not filled up.